Biological Safety Cabinets
or Fume Hoods
Which one to use?
Betty Kupskay, MSc, RBP
Biosafety Officer
Department of Environmental Health and Safety
University of Minnesota
Minneapolis, MN
[email protected]
These slides represent the opinion of the author only.
Objectives
1) To define:
 Biological Safety Cabinets (BSCs) & Fume Hoods
2) To describe:
 Similarities/differences
 When to use a BSC or a Fume Hood
 What type of BSC to use
 How to work safely in a BSC and Fume Hood
These slides represent the opinion of the author only.
Biological Safety Cabinets
These slides represent the opinion of the author only.
Introduction
What is a Biological Safety Cabinet (BSC)?

A ventilated cabinet or enclosure

Uses directional airflow and HEPA
filters to provide:
- personnel protection
- environmental protection
- varying degrees of product protection
These slides represent the opinion of the author only.
Introduction to BSCs
What is NOT a BSC?
1) A horizontal or vertical
laminar flow ‘Clean Bench’
or ‘Tissue Culture Hood’
 Discharges HEPA-filtered air across the work
surface towards the user or over the product
 Offers product protection only
 Used for sterile assembly or dust-free electronic
production/tissue culture
These slides represent the opinion of the author only.
Introduction to BSCs
What is NOT a BSC?
2) A Chemical Fume Hood

Provides protection for the user from
chemical hazards

Must not be used with biological hazards
(no HEPA filtration)
These slides represent the opinion of the author only.
Introduction to BSCs
High Efficiency Particulate Air (HEPA) filters:
 Minimum filter efficiency = 99.97% removal at 0.3
µm
 Particles larger & smaller than 0.3 µm are removed
with even more efficiency
 Pleated sheets of boron silicate
microfibers for increased surface
area
 Rigid casing enclosing full
depth of pleats
These slides represent the opinion of the author only.
Introduction
HEPA
filtration
These slides represent the opinion of the author only.
Introduction
HEPA filtration
These slides represent the opinion of the author only.
Introduction
HEPA filtration
These slides represent the opinion of the author only.
Introduction to BSCs
HEPA filters DO NOT remove vapors or
gases!!
These slides represent the opinion of the author only.
Introduction
When do we use a BSC?
In BSL2 for:


Procedures with potential to produce
infectious aerosols (incl. work with
small animals)
High concentrations or > volumes
of infectious material
Human cells

Biological toxins

These slides represent the opinion of the author only.
Introduction
When do we use a BSC?
In BSL3 & 4:
These slides represent the opinion of the author only.
Used for all manipulations
of infectious material,
except necropsies
Introduction
Types of BSCs
 Class I
 Class II (A1, A2, B1, B2)
 Class III (glove box)
These slides represent the opinion of the author only.
Class I BSC
Personnel protection: YES
 Inward air flow through sash opening
Product protection:
NO
 Unfiltered room air drawn across work surface
Environmental protection:
YES
 HEPA filtered exhaust air
Used when product protection is not required.
These slides represent the opinion of the author only.
Class I Cabinet
These slides represent the opinion of the author only.
These slides represent the opinion of the author only.
Class II BSC
Personnel protection: YES
 Inward air flow through sash opening
Product protection:
YES
 HEPA-filtered air drawn down onto work surface
Environmental protection:
YES
 HEPA filtered exhaust air to room or facility
exhaust system
Used for infectious material, biological toxins,
human cells.
These slides represent the opinion of the author only.
Class II BSC
Divided into 4 design sub-categories:
 Class II Type A1
 Class II Type A2
 Class II Type B1
 Class II Type B2
These slides represent the opinion of the author only.
Class II BSC
Class II Type A1 & A2:

70% air re-circulated; 30% exhausted to the
room or outdoors via a canopy (thimble)

Used for work with:
- Infectious agents
- Biological toxins
- Human cells
- Minute amounts of volatile chemicals &
radionuclides (only in A2 exhausted out)
These slides represent the opinion of the author only.
These slides represent the opinion of the author only.
Class II BSC
Class II Type B1:
 30% air re-circulated; 70% exhausted
 Exhausted through dedicated duct into facility
exhaust system
 Used for work with:
- Infectious agents
- Biological toxins
- Human Cells
- Minute amounts of volatile
chemicals & radionuclides
These slides represent the opinion of the author only.
These slides represent the opinion of the author only.
Class II BSC
Class II Type B2 (total exhaust):
 0% air re-circulated; 100% exhausted from cabinet
 Exhaust through dedicated duct into facility exhaust
system
 Used for work with:
- Infectious agents
- Biological toxins
- Human cells
- Small amounts of volatile chemicals &
radionuclides
These slides represent the opinion of the author only.
These slides represent the opinion of the author only.
Class III BSC (glove box)
Personnel protection: YES
 Totally enclosed ventilated cabinet; gas-tight
construction
Product protection:
YES
 HEPA-filtered air drawn down onto work surface
Environmental protection:
YES
 Double HEPA -filtered exhaust air to facility
exhaust system
BSL-4 conditions (used in a BSL-3 lab)
These slides represent the opinion of the author only.
Class III Biological
Safety Cabinet
These slides represent the opinion of the author only.
These slides represent the opinion of the author only.
Working in the BSC
Start-up Procedures:
 Turn off UV lights if used (use is discouraged)
 Turn on fluorescent light & blower, if off
 Check grilles for obstructions
 If BSC has an alarm, check & switch to ‘on’
 Disinfect all interior surfaces with 10%
bleach/70% ethanol or a suitable disinfectant
These slides represent the opinion of the author only.
Working in the BSC
Start-up Procedures:
 Work surface may be lined with plastic-backed
absorbent paper
These slides represent the opinion of the author only.
Working in the BSC
Start-up Procedures:
 Place items required for procedure into cabinet;
do not obstruct grilles
 Wait 1 minute for contaminants to purge from the
work area
These slides represent the opinion of the author only.
Working in the BSC
Start-up Procedures:
DO NOT hang spray bottles on the outside grille!
These slides represent the opinion of the author only.
Working in the BSC
Good Technique:
 Don protective clothing, gloves, respirator as
appropriate
 Enter BSC straight on
(avoid rapid & sweeping
motions)
 Position yourself with
arm pits level with top of
sash
These slides represent the opinion of the author only.
Working in the BSC
Good Technique:
 Perform operations as far to the rear of work
surface as possible
 Only one person
should be working
in a BSC at a time
These slides represent the opinion of the author only.
Working in the BSC
Good Technique:
Work from ‘clean’ to ‘dirty’
These slides represent the opinion of the author only.
Working in the BSC
Good Technique:
 Keep discarded, contaminated material to the
rear of BSC; do not discard items in containers
outside of BSC
 Vacuum lines must have a 0.22µm filter attached
on the tubing inside the BSC
These slides represent the opinion of the author only.
Working in the BSC
Good Technique:
 Do NOT use large amounts toxic or volatile
chemicals in the BSC (only small amounts
permitted in Class II B1 & B2 exhausted BSCs)
 NO OPEN FLAMES
 If BSC alarms, stop work immediately, & secure all
infectious agents
 If spill occurs, surface decon all objects; disinfect
the work surface (underneath if necessary) with
BSC ‘on’
These slides represent the opinion of the author only.
Working in the BSC
Upon completion of work:

Close open containers

Allow BSC to run for 1 min with no activity

Surface disinfect all objects in BSC before
removal from cabinet

Spray off or remove first set of gloves and
place into the biohazard bag within the BSC
These slides represent the opinion of the author only.
Working in the BSC
Upon completion of work:

Wipe down work surfaces with 10%
bleach/70% ethanol or a suitable
disinfectant

Turn off fluorescent light & cabinet blower
(ducted BSCs to be left on at all times)

Do not close sash (it is not a fume hood)!

Do not use the BSC for storage!
These slides represent the opinion of the author only.
Working in the BSC
If a spill occurs inside a BSC:
 Leave BSC ‘on’
 Don appropriate PPE
 Disinfect inside walls, work surfaces & equipment
with appropriate disinfectant
 Flood work surface & catch basin with disinfectant,
if necessary
 Let stand 30 minutes
These slides represent the opinion of the author only.
Working in the BSC
If a spill occurs inside a BSC:
 Drain disinfectant from work surface & catch basin
then autoclave or dispose down sanitary sewer
 Lift out tray & any removable exhaust grilles
 Wipe with disinfectant & replace (can autoclave
any stainless steel removable parts)
 Replace tray & grilles
 Place all contaminated materials into a biohazard
bag or pan & autoclave
These slides represent the opinion of the author only.
Working in the BSC
UV lights:
 Time of exposure, distance, presence of dust & UV
lamp intensity affect germicidal activity of UV lights
 UV light must be cleaned periodically to remove
dust
 May damage eyes, skin & laboratory equipment
 Should be turned off when room is occupied
UV lights must NOT be used for primary
disinfection of BSC.
These slides represent the opinion of the author only.
Certification of the BSC
 Correct operation must be verified before use,
then annually & after any repairs or relocation
 Field testing should be done by experienced,
qualified persons (NSF-certified)
 A copy of the certification report must be kept
by the user
These slides represent the opinion of the author only.
Certification of the BSC
Preparation of the BSC for certification:
 All equipment must be wiped/sprayed with
disinfectant, then removed
 BSC surface must be surface disinfected with a
suitable disinfectant
 Certifier may decontaminate the BSC with
formaldehyde gas or VHP
These slides represent the opinion of the author only.
These slides represent the opinion of the author only.
Certification
Label affixed on outside of BSC with:

Date of certification

Date of next certification

Standards that BSC was tested to

Name of certifier
These slides represent the opinion of the author only.
Please remember……….


Use of a BSC is a valuable supplement to
good sterile technique, not a replacement for
it
If you do not understand the BSC & how to
operate it correctly it will not offer adequate
protection for you, your product nor the
environment
These slides represent the opinion of the author only.
These slides represent the opinion of the author only.
Chemical Fume Hoods
These slides represent the opinion of the author only.
Chemical Fume Hood
Definition:
 A device with local exhaust ventilation designed
to limit exposure to hazardous or noxious fumes,
vapors, or dusts
These slides represent the opinion of the author only.
How chemical fume hoods work…
 Fume Hoods draw air out of the room & away
from the user
 An exhaust fan pulls air and airborne contaminants
from the hood through ductwork & exhausts to
atmosphere
 100% exhaust
 Shields the user with a sash (clear sliding
window) that contains aerosols & prevents injury
from splashes, fires, or minor explosions that
may occur
These slides represent the opinion of the author only.
Schematic drawing of chemical fume hood and associated ductwork
These slides represent the opinion of the author only.
When do we use a Fume Hood?
When we want to:

Contain vapors, dusts, gases, & fumes, &
remove them as air flows into the hood, then
out via the lab exhaust system
Fume hoods are not for use with biohazardous material
(i.e. no HEPA filtration)
These slides represent the opinion of the author only.
Proper Use of a Fume Hood
Ensure that the hood has a current inspection
sticker (dated within the last year)
TESTED
UNIVERSITY OF
MINNESOTA
Dept. of Environmental Health & Safety
(612) 626-6002
Velocity =_____ ______ _____ fpm
Date ______ /_______
These slides represent the opinion of the author only.
Initials_________
Proper Use of a Fume Hood
Verify the hood is working before using!
 Check the flow monitor (if present)
 Use a tissue to demonstrate flow into the hood
These slides represent the opinion of the author only.
Proper Use of a Fume Hood
Conduct all work at least 6 inches inside the hood face
Bad
Better
These slides represent the opinion of the author only.
Best
Proper Use of a Fume Hood
 The plane of the sash is the barrier between
contaminated and uncontaminated air
Never put your head inside an operating fume hood!
These slides represent the opinion of the author only.
Proper Use of a Fume Hood
Close the sash(es) to the maximum position
possible while still allowing comfortable working
conditions
Not Recommended
These slides represent the opinion of the author only.
Recommended
Proper Use of a Fume Hood
For hoods with horizontally-sliding sashes, keep
one sash in front of your body as a safety shield
These slides represent the opinion of the author only.
Proper Use of a Fume Hood
DO NOT remove sash panels or back baffles or
modify the interior or exterior components of the
hood
These slides represent the opinion of the author only.
Proper Use of a Fume Hood
DO NOT place equipment, materials or chemicals
in the hood which block the slots or otherwise
interfere with smooth hood airflow
These slides represent the opinion of the author only.
Proper Use of a Fume Hood
DO NOT place equipment, materials or chemicals
in the hood which block the slots or otherwise
interfere with smooth hood airflow
These slides represent the opinion of the author only.
BSCs vs. Fume Hoods
HEPA filtered exhaust
Worker Protection
Product Protection
Environmental Protection
Sash closed when operational
Used for Biological Hazards
Used for Biological Toxins
Chemicals
Biological Safety Cabinet
Yes
Yes
Varying degrees
Inf. agents – Yes;
Chemicals - No
No
Yes
Yes
Minute or small amts (ducted)
These slides represent the opinion of the author only.
Chemical Fume Hood
No
Yes
No
Inf. agents – No;
Chemicals – Yes (indoor)
Yes
No
No
Yes
Thank you!
These slides represent the opinion of the author only.